#include<iostream>
using namespace std;

struct TreeNode {
	int val;
	TreeNode* left;
	TreeNode* right;
	TreeNode() : val(0), left(nullptr), right(nullptr) {}
	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
	TreeNode(int x, TreeNode* left, TreeNode* right) : val(x), left(left), right(right) {}
};

class Solution {
public:
    TreeNode* pruneTree(TreeNode* root) {


        if (root == nullptr)return nullptr;

        TreeNode* left = pruneTree(root->left);
        TreeNode* right = pruneTree(root->right);

        root->left = left;
        root->right = right;

        if (root->left == nullptr && root->right == nullptr && root->val == 0)
        {
            return nullptr;
        }
        return root;
    }
};